A drive system of this type generally comprises at least one actuator or a drive motor and a mechanical system driven by it, and/or a gear unit for effecting the pivoting or sliding movement of the door, ramp, tread or the like.
Acquiring the pivoting movement of the mechanical system or of the gear unit by means of, for example, a potentiometer pick-off is known. Such a potentiometer assembly has proven in practice not to be sufficiently wear-resistant and robust in order to satisfy the high safety requirements in passenger transportation. Moreover, it is known to control or at least monitor the pivoting or sliding movement by means of switching contacts triggering at the final positions. Though a high degree of reliability can be achieved depending on the switching contact structure, and also by means of redundant components, what is a drawback in this case, however, is that these final positions are fixed once the installation and adjustment has taken place. A later adjustment, for example during the final assembly of the entry/exit facility into a passenger transport vehicle has proved to be very time-consuming due to the comparatively poor accessibility of the switching contacts. This poor accessibility on the one hand is due to the desired compactness of such drives, and on the other hand, to these switching contacts generally being disposed directly on the moving door, ramp, tread etc., for example on their associated pivoting pins, and not on the driving mechanical system, in order thus to be certain these moving elements, such as the door, ramp, tread etc. are actually in the state displayed by the state of the switching contact, for example open or closed. Furthermore, it was found that during operation, a later adjustment is often required during the operating life of the vehicle because of wear and the accompanying increasing clearance between the mechanically interacting components.